The present invention is related to the technical field of liquid dosing, in particular to sample preparation dosing units, to sample preparation devices comprising such dosing units as well as to corresponding methods for liquid dosing in sample preparation devices.
The application WO 99/26070 discloses the usage of two separate pumps which are designed for different flow rates and used for alternatively dosing chemical reagents or a cleaning liquid.
The application US 2004/0028565A1 discloses an arrangement with two coupled piston pumps and controlled valves for sequentially dosing a reagent and a cleaning liquid. This design, however, is complex and restricted to carrying out cycles of dosing reagent, followed by subsequent cleaning.